The present invention relates to an electron beam system, a defect inspection apparatus for a device, which employs the same electron beam system, and a manufacturing method of a device using the same defect inspection apparatus, and more specifically, relates to an electron beam system which can evaluate a sample (a semiconductor wafer) having a device pattern with a minimum line width equal to or less than 0.1 μm with both a high throughput and high reliability, a defect inspection apparatus for a device, which employs the same electron beam system, and a manufacturing method of a device which can improve a yield thereof by evaluating a wafer after it has been processed using the same defect inspection apparatus.
The present invention also relates to an electron beam system and a defect inspection method for evaluating a device, such as a wafer or a mask, having a pattern with a minimum line width in a range of 0.1 micron, and also to a method for manufacturing a device with a high yield by using the same system and a defect inspection method.
The present invention further relates to a method for simplifying a registration (positioning) of an inspection apparatus in which an electron beam is irradiated against a sample and secondary electrons emanated from the sample are detected and then processed to thereby obtain an SEM (Scanning Electron Microscope) image of a fine geometry on a surface of the sample, and thus carry out evaluation thereof. The fine geometry on the sample surface may be, for example, on a semiconductor wafer or a mask having a high-density pattern with a minimum line width equal to or less than 0.1 μm. The present invention also relates to a manufacturing method of a semiconductor device using such an inspection apparatus.
One such electron beam system has been suggested for evaluating a sample having a device pattern with a minimum line width equal to or less than 0.1 μm, in which a shaped electron beam is demagnified (contracted) to be narrower and irradiated onto a sample and then secondary electrons emanated from the sample are detected so as to evaluate the sample. In such a system, an optical system for shaping the electron beam has employed at least a three-stage of lenses. Besides, when it is intended to form such a narrow electron beam equal to or less than 0.1 μm, a demagnification crossover image type beam has been employed. Further, it is required to increase an intensity of the electron beam in order to provide evaluation with higher reliability, and in this case a thermoelectric field emission (schottky) cathode electron gun has been used so as to obtain a high current beam of 0.1 μm or smaller.
Such an electron beam system has been known, in which a primary electron beam emitted from an electron gun is demagnified to be narrower so as to irradiate a sample, such as a wafer or a mask, and a secondary electron beam, which has been emanated from the sample through this irradiation, is detected, to thereby detect any defects or to measure a line width on the sample. Further, it has been also known that an electron beam is irradiated on a sample and thereby charges are introduced to a pattern on the sample so as to induce a voltage, which is in turn measured and thus an electric parameter of the sample is measured.
In the prior art, for measuring the voltage induced in the pattern on the surface of the sample, there has been employed one such method in which a hemispherical mesh filter is provided, and the secondary electrons emanated from the sample surface are returned to the sample surface side or introduced into a detector arranged behind the mesh in dependence on a potential of the pattern from which the secondary electrons have been emanated, thus carrying out measurement of the potential of the pattern. An electron gun in an electron beam system to be used in such a method may be in most cases one designated as a schottky type by Zr—W having a magnified intensity. Further, a demagnified crossover image formed by the electron gun has been commonly used as a probe current for injecting charges into the sample to measure the voltage of the pattern.
One such inspection apparatus has been well known that uses a scanning electron microscope to inspect a subject (sample), such as a semiconductor wafer and so on. In this inspection apparatus, a narrowly demagnified electron beam is used to conduct raster scanning with a raster scanning width of an extremely narrow space, and then secondary electrons emanated from the subject are detected by a detector so as to form an SEM image, wherein two SEM images for corresponding locations in two different samples are compared to each other to detect any defects.
A lithography apparatus which comprises an electron optical system and which uses an electron beam to form a fine geometry on a surface of a sample such as a semiconductor wafer requires position alignment or a registration of high precision between the electron optical system and the sample. In order to satisfy this requirement, one method has been employed that uses the electron optical system of the lithography apparatus to detect an alignment mark on the sample to accomplish the position alignment, and also another method has been employed, in which an optical microscope is further provided in addition to the electron optical system so as to perform rough alignment (a roughly controlled position alignment) through an observation across an enlarged field of view by using the optical microscope and also fine alignment (a high magnification position alignment) by using the electron optical system of the lithography apparatus. However, such high precision alignment is not necessarily required in an inspection apparatus.